PD20SL-4 / C-7401
20 sq ft replacement filter cartridge • 7″ OD × 6.5″ long
Doughboy's smallest cartridge filter, rated at 20 square feet, takes this stubby element: 7 inches across but only 6-1/2 inches tall, with an injection-molded closed knob on top and an open bottom. Doughboy numbers it 2396-020, and the Unicel cross-reference is C-7401. There's no Filbur equivalent listed. All four Doughboy cartridges share the same 7-inch diameter and differ only in height, so length is what tells the 20, 40, 60, and 90 apart. This is the short one, suited to smaller above-ground pools. If your Doughboy filter is taller than about 6-1/2 inches, you've got one of the bigger sizes, so measure before you order.
Compare on Amazon
PD20SL-4 replacements on Amazon
The buttons below pull up Amazon results for each cross-reference part number. Same physical cartridge, different stickers, often different prices. Cross-shop and pick the cheapest option that has solid recent reviews.
Cross-Reference & Interchangeable Part Numbers
| Brand | Part Number | Type |
|---|---|---|
| Pleatco | PD20SL-4 | Primary |
| Unicel | C-7401 | Equivalent |
| OEM | Doughboy 2396-020 | Original Equipment |
Always verify dimensions and end-cap type before purchasing a replacement.
Compatible Pool Filter Systems
| Brand | Model |
|---|---|
| Doughboy | 20 sq ft Pool Filter |
Frequently Asked Questions
What are the dimensions of the PD20SL-4?
The PD20SL-4 is 7 inches in outer diameter, 6.5 inches long, with a closed top and an open bottom. Total filtration area is 20 square feet. Before ordering, pull your existing cartridge and measure it yourself, or check the label inside the housing. OD and length both have to match within about an eighth of an inch, and the end-cap style needs to match exactly so the cartridge seats properly when the lid closes.
What other part numbers are interchangeable with the PD20SL-4?
PD20SL-4 is the same physical cartridge as C-7401, plus OEM versions like Doughboy 2396-020. Same dimensions (7" × 6.5"), same closed top, same open bottom. The Pleatco, Unicel, and Filbur boxes ship the same media inside, just with different stickers. The only thing to watch is the end-cap style: if a cross-reference has a slightly different cap design, it may not seat right in your housing.
Is the Doughboy 2396-020 the same filter as the PD20SL-4?
Yes. Doughboy 2396-020 is an OEM number, the code the tub or pool builder stamps on the cartridge they ship. The filter itself is made by Pleatco, Unicel, or Filbur, so Doughboy 2396-020 and PD20SL-4, C-7401 all point to one interchangeable cartridge. Buy whichever is cheapest with solid recent reviews, and just check that the dimensions match your old cartridge before you order.
How often should I replace the PD20SL-4?
At 20 sq ft the PD20SL-4 runs smaller than the big 100-plus sq ft pool cartridges, so it has less buffer between cleanings. Expect 12 to 18 months in normal use, less if the pool sees heavy traffic or the chemistry drifts. Watch the gauge: when pressure sits 8 to 10 psi above the clean starting point and a soak won't drop it, put in a fresh one.
How do I clean the PD20SL-4?
The PD20SL-4 has a closed (solid) top cap, so water enters through the side and drains through the bottom only. Pull the cartridge from the housing and hose it down. Hit the pleats from above at about a 45-degree angle so water rinses debris out instead of packing it deeper, and work top to bottom while rotating the cartridge. Skip the pressure washer. The high pressure tears or collapses pleats, and once that happens you've lost media that doesn't come back. Every few months, give it a deeper clean: soak in a dedicated pool filter cleaner per the product's dwell time, then rinse it down completely before reinstalling. Keeping a spare cartridge on the shelf is genuinely worth it. You swap, run the soak overnight, and the pool keeps filtering.
Which hot tubs and spas use the PD20SL-4?
Pull your existing cartridge and read the part number off the end cap, or check the label inside the filter compartment. That's the most reliable way to confirm compatibility.
Dimensions
Specifications
| Outer Diameter | 7″ |
|---|---|
| Length | 6.5″ |
| Top Type | Closed (solid end cap) |
| Bottom Type | Open (no end cap) |
| Filtration Area | 20 sq ft |
| Primary Brand | Pleatco |
| Part Number | PD20SL-4 |
Fitment notes
Injection molded knob/closed top. Doughboy 20 sq ft pool filter.